She's Right Behind Me, Isn't She?

Ever put one of your characters in that awkward situation where they're talking trash or making fun about someone and suddenly the person in question is standing right behind them? And isn't it so funny when it happens...to someone else? 

While I was procrastinating on the net doing research for my ms, I came across this clip that compiles a bunch of movie examples of the "(S)he's right behind me..." moments. It's pretty funny but I kept waiting for the scene from Kung Fu Panda where Po is making fun of Master Shifu with the noodle bowls for ears and a string of noodle draped over his nose, know what I'm talking about? That scene totally cracks me up but I couldn't find it online. Anyway, enjoy the clip below, it has a bunch of funny moments.  (:

Do you all have other examples? Written this into your wip? Has this ever happened to you in real life? Oh, if it has please share! :D